JP2003051573A - Power module and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power module in which a heat generated by an electronic component is uniformly and efficiently radiated and which can be mounted in high density, and to provide a method for manufacturing the same. SOLUTION: The power module comprises a circuit board (103) in which a heating component (101) is electrically connected and which is connected to a heat sink (105) via a heat conductive electric insulating member (104). In this module, the insulating member (104) is a curable composition containing a thermosetting resin (A), a thermoplastic resin (B), a latent curing agent (C), and an inorganic filler (D). The insulating member is adhered to the heating component in a state in which the member is complementarily deformed to unevennesses of a shape of the heating component and a component height. A heat generated by the component (101) is radiated by the heat sink (105).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power module for mounting an electronic component such as a power semiconductor device that generates a large amount of heat and used for power conversion and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, with the demand for high performance and miniaturization of electronic equipment, there is a demand for miniaturization and energy saving of power circuits used in the power electronics field. Therefore, the heat dissipation structure of the power module has become an important issue.

As a method for improving the heat dissipation of the power module, there is used a method in which a heat sink is attached to an electronic component such as a semiconductor chip which generates a large amount of heat and heat is radiated from the heat sink. The heat generating component and the heat sink are kept in thermal contact with each other by a member having insulation and heat conductivity.
Thermal conductive grease is mentioned as such a member. However, the heat conductive grease is not easy to handle, and the degree of thermal contact differs depending on the coating method.
A method is used in which a heat conductive elastic sheet is sandwiched and pressed between the heat generating component and the heat sink so as to be fixed and brought into contact with each other.

On the other hand, as another method for improving the heat dissipation of the power module, a substrate having good heat conductivity is used.
Another method is also used in which heat-generating components are mounted on this board to radiate heat from the board. As such a heat dissipation substrate, for example, there is a substrate in which a copper plate is bonded to the surface of a ceramic substrate such as aluminum oxide or aluminum nitride, but it has a problem of high cost, and is used for relatively low power applications. Generally, a metal base substrate in which a wiring pattern is formed on one surface of a heat sink such as aluminum via an insulating layer is used. However, the metal base substrate needs to have a thin insulator in order to improve heat conduction, and thus has a problem in that it is affected by noise between the metal bases and has a withstand voltage.

As described above, since it is difficult to make the ceramic substrate and the metal base substrate compatible with each other in terms of performance and cost, there has been proposed a substrate having a lead frame formed on the surface of a substrate in which an inorganic filler is dispersed in a thermoplastic resin. However, since this substrate is produced by melt-kneading a thermoplastic resin and an inorganic filler and injection-molding this, it is difficult to fill the inorganic filler in a high concentration, and the thermal conductivity is improved. Is limited. Further, a method of using a substrate having a lead frame formed on the surface of a substrate in which an inorganic filler is dispersed in a thermosetting resin composition has been proposed (JP-A-10-173097). This substrate is produced by stacking a flexible sheet-shaped material containing a thermosetting resin and an inorganic filler and a lead frame in an uncured state, and then curing the sheet-shaped material to enhance the inorganic filler. It can be filled to a high concentration, achieving good thermal conductivity.

[0006] These heat-radiating substrates have single-sided wiring and a single wiring layer, and it is extremely difficult to route fine wiring. In a power module such as an inverter, a power circuit section including heat-generating components is mounted on these heat dissipation boards, and a control circuit section that requires relatively small heat generation, such as a drive circuit and a protection circuit, is a component with relatively little heat generation. It is provided on a control board that is a printed wiring board. The control board is assembled separately from the heat dissipation board on which the power circuit section is formed, and then electrically connected to the heat dissipation board. For example, on a mounting surface of a heat dissipation board on which components are mounted, control boards are arranged facing each other with a certain space therebetween, fixed, and packaged.

A power module using such a heat conductive elastic sheet or a heat dissipation substrate has the following problems.

Since the heat conductive elastic sheet is thin, it has a problem of low withstand voltage. In addition, when a plurality of heat-generating components and one heat sink are brought into thermal contact with each other via an elastic sheet, the height of the heat-generating components mounted on the board may be uneven, dimensional tolerances, and mounting attitudes with respect to the board may vary. It is necessary to absorb variations in the component height based on the deformation of the elastic sheet due to pressing. Therefore, in the case of a thin elastic sheet, there is a limit to the variation of the component height that can be absorbed, and if the variation is large, there is a problem that a uniform degree of contact between the elastic sheet and the heat-generating component cannot be maintained. Further, there is also a problem that the stress caused by excessive pressing of the elastic sheet against the heat-generating component causes damage to the heat-generating component and cracks in the elastic sheet.

On the other hand, the power module using the heat dissipation substrate has the following problems. In other words, the number of connection terminals increases, even for heat-generating components that require heat dissipation,
In addition, when the pitch between the electrodes is narrow, it is necessary to lay out fine wiring, and it is difficult to mount the wiring on a single-sided and single-layer wiring for heat dissipation with high density. However, if this heat generating component is mounted on a control board that allows fine wiring but has poor thermal conductivity, it is difficult to dissipate heat. Therefore, there is a problem that it is not suitable for a heat-generating component that requires both fine wiring and heat dissipation.

As a method of mounting a semiconductor chip,
Generally, there are a wire bonding method and a flip chip mounting method. In the flip chip mounting, a semiconductor chip is mounted face down on a substrate so that the substrate surface and the semiconductor chip surface (electrode forming surface) face each other. Therefore, higher density mounting is possible as compared with the wire bonding method. However, in a power module using a heat dissipation substrate, it is necessary to have a structure that dissipates heat from the substrate, and if the flip chip mounting method is adopted, improvement in heat dissipation cannot be expected, so semiconductors as heat generating components cannot be expected. The chip is mounted on the heat dissipation substrate with its back surface (the surface opposite to the electrode formation surface) in contact with the substrate surface to dissipate heat from the board. Therefore, a wire bonding method is used in which the electrodes of the semiconductor chip and the electrodes on the heat dissipation substrate are connected by a thin metal wire. However, in the wire bonding method, the conductor resistance of the thin metal wire is so large that it cannot be ignored as compared with the on-resistance of the semiconductor element. Therefore, mounting the semiconductor chip by the wire bonding method increases power loss and heat generation. Therefore, in the power module using the heat dissipation substrate, since the semiconductor chip that generates a large amount of heat is mounted by the wire bonding method, there is a problem that further heat dissipation is required for the substrate.

[0011]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention makes it possible to achieve both fine wiring required for a heat-generating component with a large number of connecting terminals and high heat dissipation, and to achieve high-density miniaturization. It is an object of the present invention to provide a power module suitable for, and a manufacturing method thereof.

[0012]

In order to achieve the above object, in the first power module of the present invention, a heat generating component electrically connected to a wiring board and a heat sink are provided with a heat conductive electrically insulating member. In the power module, the thermally conductive electrically insulating member comprises a thermosetting resin (A), a thermoplastic resin (B), and a latent curing agent (C).
And a cured composition containing an inorganic filler (D), wherein the thermally conductive and electrically insulating member is adhered to the heat-generating component in a state complementary to the irregular shape and shape of the heat-generating component. The heat sink dissipates heat generated from the heat generating component.

A second power module of the present invention is provided with a metal ball on the front surface of the semiconductor chip, a wiring board on the front surface, and a heat spreader in close contact with the entire back surface of the semiconductor chip. Heat is dissipated from the side, and a current flows through the semiconductor chip in the thickness direction.
The semiconductor chip between the wiring board and the heat spreader, the metal ball on the surface of the semiconductor chip, and the extraction electrode are resin-sealed, the extraction electrode electrically connecting the heat spreader and the wiring board.

Next, in the method for manufacturing a power module of the present invention, a step of mounting an electronic component including at least a heat-generating component on a wiring board, a thermosetting resin (A), a thermoplastic resin (B), and a latent Curing agent (C) and inorganic filler (D)
Is formed between the heat sink and the heat generating component side of the wiring board, at least one selected from the heat sink and the wiring substrate is pressed against the other, and the shape and component height of the heat generating component. The step of complementary deformation and adhesion of the heat conductive electrical insulating member to the unevenness of the above, and the step of heating to cure the curable composition layer to form the heat conductive electrical insulating member. And

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION According to the present invention, heat-generating components can be mounted at high density on a wiring board on which fine wiring is formed, and the heat generated from the heat-generating components is The heat is instantly radiated from the heat sink via the heat conductive electrically insulating member adhered to the heat sink. Furthermore, the heat conductive electrically insulating member is deformed in a complementary manner, resulting in uneven heights and dimensional tolerances of heat-generating components mounted on the wiring board.
Since the variation in mounting posture with respect to the wiring board is absorbed, the heat generated from each heat-generating component can be uniformly and efficiently dissipated without being influenced by the variation in component height.
Further, since the heat conductive electrically insulating member is bonded to the heat generating component and the heat sink, the contact heat resistance is low and the heat dissipation efficiency is high. Further, since the heat conductive electrically insulating member is adhered by itself, no external force is required to bring the heat generating component into close contact with the heat generating component, and a stress is not applied to the heat generating component.

With respect to the total amount of 100 parts by mass of the thermosetting resin (A) of 50 parts by mass or more and 95 parts by mass and the latent curing agent (C) of 5 parts by mass or more and 50 parts by mass or less, The thermoplastic resin (B) is in the range of 10 parts by mass or more and 100 parts by mass or less, and the total amount of the thermosetting resin (A), the thermoplastic resin (B), and the latent curing agent (C) is 5 parts by mass. It is preferable that the inorganic filler (D) is in a range of 70 parts by mass or more and 95 parts by mass or less with respect to parts by mass or more and 30 parts by mass or less.

It is preferable that the thermosetting resin is liquid at room temperature and the thermoplastic resin is powdery when the thermosetting resin is uncured.

The insulative resin constituting the heat conductive resin composition contains a thermosetting resin which is liquid at room temperature as a main component, contains at least a thermoplastic resin and a latent curing agent, and in the uncured state, the above-mentioned thermoplastic resin is used. Compositions in which the resin is a thermoplastic resin powder are preferred. Such a composition is capable of irreversibly solidifying by increasing the viscosity in the uncured state by the thermoplastic resin powder absorbing the liquid component and swelling. Further, it can be cured by heating to a temperature above the activation temperature of the latent curing agent.

As the thermosetting resin which is liquid at room temperature, various kinds such as liquid epoxy resin and liquid phenol resin can be used. In the present invention, the liquid epoxy resin is particularly preferable from the viewpoint of heat resistance and electric insulation. Examples of such liquid epoxy resin include bisphenol A type epoxy resin,
Bisphenol F type epoxy resin, Bisphenol AD
Type epoxy resin, phenol novolac type epoxy resin and the like can be used.

The latent curing agent is not particularly limited,
A known material can be used, which is selected according to the type of thermosetting resin used. For the liquid epoxy resin, for example, a dicindiamide curing agent, a urea curing agent, an organic acid hydrazide curing agent, a polyamine salt curing agent, an amine adduct curing agent, or the like can be used.

The thermoplastic resin powder is not particularly limited as long as it has a property of absorbing and swelling a liquid component contained in an insulating resin containing a liquid thermosetting resin as a main component, and is not particularly limited, but it is used. A material that swells is selected according to the type of thermosetting resin. For liquid epoxy resins,
Polyvinyl chloride, polymethyl methacrylate, polyethylene, polyamide and the like are preferable. The average particle size of the thermoplastic resin powder is preferably 1 to 100 μm. The mixing amount of the thermoplastic resin powder in the insulating resin may be a sufficient amount so that the thermoplastic resin powder absorbs the freely flowing liquid component and the mixture is substantially solidified. It is 10 to 100 parts by mass, preferably 20 to 60 parts by mass, relative to 100 parts by mass of the thermosetting resin. Swelling of the liquid component of the thermoplastic resin powder is promoted by the heat treatment.
This heat treatment is carried out at a temperature above the softening point of the thermoplastic resin powder and below the melting point. In this case, it is desirable to perform at a temperature not higher than the curing temperature of the thermosetting resin contained in the insulating resin so as to maintain the state of the thermosetting resin at least in the temporary curing reaction stage, and the heat treatment temperature is 70 to 110 ° C. It is desirable to operate in the temperature range. The heating time may be sufficient so that the insulating resin is substantially solidified.

The inorganic filler constituting the heat conductive resin composition is Al ₂ O ₃ , MgO, BN or SiO which is excellent in heat conductivity.
It is desirable that it is at least one kind of filler selected from ₂ , SiC, Si ₃ N ₄ and AlN. The average particle diameter of the inorganic filler is preferably in the range of 0.1 to 100 μm, and more preferably 7 to 12 μm.

The content of each component in the heat conductive resin composition is such that the total amount of the heat conductive resin composition is 100 parts by mass.
5 to 30 parts by mass of the insulating resin, preferably 7-1
5 parts by mass, more preferably 9 to 12 parts by mass, and the inorganic filler is 70 to 95 parts by mass, preferably 86 to 93 parts by mass, and more preferably 89 to 93 parts by mass. Thereby, the thermal conductivity of the thermally conductive electrically insulating member, which is a cured product of the thermally conductive resin composition, can be improved.

Further, the heat conductive resin composition preferably contains additives such as a coupling agent, a dispersant, a coloring agent and a release agent, if necessary. This is because the inclusion of various additives makes it possible to improve the characteristics of the insulating layer. For example, the coupling agent is effective in improving the withstand voltage because it improves the adhesion between the inorganic filler and the insulating resin. Further, the dispersant improves the dispersibility of the inorganic filler and is effective in reducing the compositional unevenness in the heat conductive electrical insulating member. Further, if the colorant is, for example, a black colorant such as carbon powder, it is effective in improving heat dissipation.

The thermosetting resin (A), the thermoplastic resin (B), the latent curing agent (C) and the inorganic filler (D).
Of the curable composition containing a steep primary viscosity increase curve at 70 ° C or higher and lower than 130 ° C and a steep second curve at 130 ° C or higher
It is preferable to have a characteristic of a secondary viscosity increase curve. This will be described with reference to FIG. In FIG. 10, a curve X shows the temperature and viscosity characteristics of the composition of the conventional thermosetting resin and the curing agent. Above about 100 ° C, the viscosity simply increases gradually with increasing temperature.

On the other hand, the composition of the present invention has a curve Y, a steep first-order viscosity increase curve Y ₁ at 70 ° C. or higher and lower than 130 ° C. and a second steep second curve at 130 ° C. or higher and 220 ° C. or lower. The next viscosity increase curve Y ₂ is developed. The expression of the primary viscosity increase curve Y ₁ is due to the addition of the thermoplastic resin, and the thermoplastic resin absorbs the liquid component at a temperature of 70 ° C. or higher and lower than 130 ° C. to cause a rapid viscosity increase. Next, the expression of the secondary viscosity increase curve Y ₂ is due to the addition of the latent curing agent, and the curing reaction rapidly advances at 130 ° C. or higher and 220 ° C. or lower, and the viscosity increases.

In the power module, the heat conductive electrical insulating member is bonded to the plurality of heat generating components, and the plurality of heat generating components are thermally coupled to the heat sink via the common heat conductive electrical insulating member. It is desirable to be connected to. Thereby, it is not necessary to dispose the heat conductive and electrically insulating member for each heat generating component, and the heat generating component can be manufactured more easily.

In the power module,
It is desirable that non-heat generating components are further mounted on the wiring board on which the heat generating components are mounted. As a result, the power circuit unit including the heat generating component and the control circuit unit including the non-heat generating component can be integrated and mounted on the same wiring board with high density, and the power module can be further downsized.

In this case, it is desirable that the heat generating component is mounted on one main surface of the wiring board and the non-heat generating component is mounted on the opposite surface. As a result, even if the non-heat-generating component of the control circuit unit is extremely vulnerable to heat, the control circuit unit and the power circuit unit can be integrated without impairing its function due to heat from the heat-generating component of the power circuit unit. .

In the power module,
The heat conductive electrically insulating member is the insulating resin 5 to 30.
It is desirable that the cured product of the heat conductive resin composition comprises 70% by mass of the inorganic filler and 70 to 95% by mass of the inorganic filler. As a result, the heat conductivity of the heat conductive electrically insulating member can be improved, and the heat dissipation can be more reliably improved.

In the power module,
The insulating resin contains at least a thermosetting resin that is liquid at room temperature in an uncured state, a thermoplastic resin, and a latent curing agent, and the thermoplastic resin is a thermoplastic resin powder in an uncured state. desirable. With this, the heat conductive electrical insulating member is bonded to the heat generating component and the heat sink as a cured product of the thermosetting resin, so that the contact thermal resistance can be reduced. Moreover, the heat sink can be fixed to the heat-generating component without a complicated fixture. Such a composition can be irreversibly solidified by increasing the viscosity in an uncured state by heat-treating the composition so that the thermoplastic resin powder absorbs the liquid component and swells it. Further, it can be cured by heating. The room temperature is
It is usually 20 ° C.

In this case, the thermosetting resin which is liquid at room temperature is preferably liquid epoxy resin. Heat-resistant,
This is because it has excellent electrical insulation.

In the power module,
The inorganic filler is Al ₂ O ₃ , MgO, BN, SiO
It is desirable that it is at least one kind of filler selected from ₂ , SiC, Si ₃ N ₄ and AlN. This is because these inorganic fillers have excellent thermal conductivity and are particularly effective in improving the thermal conductivity of the thermally conductive electrically insulating member.

In the power module,
The thermal conductivity of the thermally conductive electrically insulating member is 1 to 10 W /
It is preferably in the range of mK. Thereby, the heat dissipation of the power module can be more surely improved.

In the power module,
At least one semiconductor device may be used as the heat generating component.

In the power module,
The heat generating member may be a plurality of heat generating components having different heights.

In the power module,
It is preferable that a complementary state of the thermally conductive and electrically insulating member is formed by pressing.

Further, at least one of the semiconductor elements is provided with a heat spreader on a surface opposite to a surface electrically connected to the wiring board, and the heat spreader is resin-sealed with at least a part thereof exposed. It is desirable that at least the exposed surface of the heat spreader is bonded to the heat conductive electrically insulating member. Thereby, the heat generated by the semiconductor element is instantaneously transmitted to the heat spreader, and the heat can be efficiently radiated toward the heat conductive electrically insulating member. In the present invention, the heat spreader means a heat diffusion plate.

Further, it is preferable that the semiconductor element is a semiconductor chip, the semiconductor chip is mounted face down on the wiring board, and the back surface of the semiconductor chip is bonded to the thermally conductive and electrically insulating member. As a result, since heat is radiated from the back surface of the semiconductor chip, it is possible to perform high-density mounting because it is mounted face down, so that power loss and heat generation can be reduced compared to mounting by wire bonding. .

The semiconductor element is a semiconductor chip, the semiconductor chip is mounted face down on the wiring board, and the back electrode of the semiconductor chip is electrically connected to the wiring board via a metal conductor. Is desirable. As a result, even if the semiconductor chip has electrodes on the back surface, it is possible to perform high-density mounting because it is mounted facedown while radiating heat from the back surface of the semiconductor chip, compared to mounting by wire bonding. The power loss is reduced and the amount of heat generation can be reduced.

Further, in the power module using the semiconductor chip, it is desirable that a resin is sealed between the semiconductor chip mounted face down and the wiring board. As a result, the reliability of the electrical connection between the semiconductor chip and the wiring board can be improved. Further, it plays a role of reinforcing the fixing of the semiconductor chip onto the wiring board.

The semiconductor chip is an isolation gate bipolar transistor (IGBT), which is a silicon semiconductor that allows a current to flow in the thickness direction of the chip.
r transistor), metal-oxide semiconductor field-effect transistor (MOS-FET)
or a single crystal SiC semiconductor which is a silicon carbide semiconductor can be used.

In the power module,
Desirably, the heat sink is aluminum or copper. This is because these metals have excellent thermal conductivity. In particular, copper is excellent in heat conductivity, so that good heat dissipation can be obtained. Further, since aluminum is light in weight and can be obtained at low cost, and has excellent workability, it is possible to form the heat sink in a complicated shape to increase the surface area, and it is possible to obtain good heat dissipation.

In the power module,
It is desirable that the heat sink be fixed to the wiring board by a fixture. This makes it possible to more firmly fix the heat sink bonded to at least the heat-generating component by the heat conductive electrically insulating member.

In the power module,
It is preferable that the heat sink has a recess, and at least the heat-generating component is housed in the recess via the heat-conductive electrically insulating member. Thereby, the arrangement of the thermally conductive and electrically insulating member can be restricted within the recess of the heat sink, and the manufacturing can be easily performed.

In the power module,
It is desirable that the heat sink includes a radiation fin. Thereby, heat dissipation efficiency can be improved more reliably.

Next, in the manufacturing method of the present invention, the thermoplastic resin powder is allowed to swell by absorbing a liquid component by heat treatment, thereby increasing the viscosity of the uncured thermally conductive electrically insulating member to make it non-curable. The heat sink can be reversibly solidified, the heat sink is fixed to the heat generating component, and then the heat conductive electrically insulating member can be cured by heating. As a result, the adhesiveness between the heat-generating component and the heat sink can be inspected in a state where the heat-conducting electrically insulating member is not yet cured but is solidified.

Further, the uncured heat conductive electrical insulating member arranged on the heat sink is heat-treated before being brought into close contact with the heat generating component, so that the thermoplastic resin powder absorbs the liquid component and swells to have a viscosity. The heat-conducting electric insulation is raised and irreversibly solidified, and the heat-conducting electrical insulating member is deformed and adhered to the irregular shape of the heat-generating component in a complementary manner, and then heated to heat-conducting the electrical insulating member. The member can also be cured. Accordingly, even when the uncured heat conductive electrical insulating member has high fluidity, the viscosity can be increased by the swelling of the thermoplastic resin powder, and excessive outflow in the step of closely contacting the heat generating component can be prevented.

Further, a heat conductive resin composition comprising an inorganic filler and an insulating resin containing at least a thermosetting resin which is liquid at room temperature, a thermoplastic resin powder and a latent curing agent is used in the uncured state of the heat conductive electrical conductive material. It is used as an insulating member and is placed on each of the heat-generating components, and after it is brought into close contact with a heat sink, it is heat-treated to absorb the liquid component into the thermoplastic resin powder so that the thermoplastic resin powder swells, so that the uncured thermal conductive electricity The viscosity of the insulating member is increased to irreversibly solidify,
The heat sink may be fixed to the heat generating component and then heated to cure the heat conductive electrically insulating member. As a result, it is possible to inspect the adhesiveness between the heat-generating component and the heat sink in the uncured but solidified state before the heat conductive electrically insulating member is cured.

In the method of manufacturing the power module, the step of mounting the heat-generating component on the wiring board is such that after mounting the semiconductor chip face down, a sealing resin is placed between the wiring pattern on the wiring board and the semiconductor chip. It is desirable to be a process of injecting and curing. This allows
Since the fixing of the semiconductor chip mounted face down on the wiring board is reinforced by the sealing resin, the step of bringing the uncured thermally conductive electrically insulating member into close contact with the heat generating component or the heat sink can be easily performed. it can.

In the method for manufacturing the power module, the step of disposing an uncured heat conductive electrically insulating member made of the heat conductive resin composition on a heat sink is a paste of the heat conductive resin composition. It is desirable that this is a step of applying the object. This makes it possible to obtain a heat conductive electrically insulating member in which the inorganic filler is filled in a high concentration, and it is possible to obtain a power module having excellent heat dissipation. Further, it can be formed with simple equipment.

In the method of manufacturing the power module, the step of disposing the uncured heat conductive electrically insulating member made of the heat conductive resin composition on the heat sink has flexibility in the uncured state. It is desirable that this is a step of laminating a sheet-shaped material of the heat conductive resin composition on the heat sink. This makes it possible to obtain a heat conductive electrically insulating member in which the inorganic filler is filled in a high concentration, and it is possible to obtain a power module having excellent heat dissipation. It can also be easily placed on the heat sink.

In the method for manufacturing the power module, the step of swelling and solidifying the thermoplastic resin powder by the heat treatment is preferably carried out at a temperature range of 70 to 130 ° C, more preferably 70 to 110 ° C. . Thereby, the swelling of the thermoplastic resin powder can be promoted while the thermally conductive electrically insulating member remains in the uncured state.

In the method for manufacturing the power module, the step of bringing the heat-generating component into close contact with the heat-conductive electrical insulating member and / or the step of heating and hardening the heat-conductive electrical insulating member is 0.1 MPa. 200 MPa or more
It is desirable to carry out under the following pressure. As a result, the heat conductive electrical insulating member can be reliably brought into close contact with the heat generating component or the heat sink, and further, voids in the heat conductive electrical insulating member that cause a decrease in withstand voltage can be reduced. .

Further, in the method of manufacturing the power module, during the step of arranging the heat conductive electrical insulating member to the step of curing, or the step of closely contacting the heat generating component and the heat conductive electrical insulating member. Immediately after carrying out, it is desirable to add a step of exposing the formed product under reduced pressure. As a result, voids in the thermally conductive electrically insulating member that cause a decrease in withstand voltage can be reduced.

In the method of manufacturing the power module, it is preferable that the step of heating and hardening the heat conductive electrically insulating member is in the range of 130 to 260 ° C. As a result, the thermosetting resin that constitutes the heat conductive electrically insulating member can be cured in a short time.

In the method of manufacturing the power module, a step of fixing the heat sink to the wiring board with a fixture may be added before or after the step of heating and hardening the heat conductive electrically insulating member. Is desirable. This makes it possible to more firmly fix the heat sink bonded to at least the heat-generating equipment by the heat conductive electrically insulating member.

In this case, it is also effective that the step of closely contacting the heat generating component and the heat conductive and electrically insulating member is performed at the same time as the step of fixing the heat sink to the wiring board with a fixture. As a result, the heat sink can be reliably arranged with respect to the heat generating component, and the manufacturing can be performed more easily.

In the method of manufacturing the power module, instead of the step of heating and curing the heat conductive electrical insulating member, the solidified uncured heat conductive electrical insulating member and the heat generating component are replaced. Alternatively, from the step of inspecting the adhesion with the heat sink and the step of removing the thermally conductive electrical insulating member, and again disposing the uncured thermally conductive electrical insulating member, the thermal conductivity It is also effective to carry out the step of heating and curing the electrically insulating member. By this repair process, the power module of the present invention can be manufactured with high yield.

Next, the second power module of the present invention is useful as a component for producing the first power module.

In the power module of the present invention, the back surface of the heat-generating component that is electrically connected to the wiring board is provided with a heat-conducting electrically insulating member filled with a high concentration of an inorganic filler, which is affected by variations in component height. It is adhered uniformly without the heat sink being thermally connected to the heat sink adhered to the opposite surface.

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a sectional view showing the structure of a power module according to Embodiment 1 of the present invention. As shown in FIG. 1, the power module includes a wiring board 103 to which a heat-generating component 101 is electrically connected, and a heat sink 105 that is thermally connected to the heat-generating component via a thermally conductive electrically insulating member 104. The heat conductive electrical insulating member is bonded to the heat generating component in a state of being deformed in a complementary manner with respect to the shape of the heat generating component and the unevenness of the component height.

The heat conductive electrical insulating member 104 is a layer in which an inorganic filler is dispersed in an insulating resin, and the thermal conductivity and the linear heat of the heat conductive electrical insulating member are selected by selecting the insulating resin and the inorganic filler. It is possible to adjust the expansion coefficient, the dielectric constant, etc., but the thermal conductivity is preferably 1 to 10 W / m.
By setting it in the range of K, it becomes a power module having good heat dissipation. In addition, in FIG. 1, a group of a plurality of heat-generating components has a preferable configuration in which it is thermally connected to a heat sink via a common heat conductive electrically insulating member. However, as shown in FIG. The heat-conducting electrically insulating member may be bonded to the heat-generating component. In FIG. 2, the wiring board 2
03 heat generating parts 201 and 206 and non-heat generating part 2
02 is mounted, and a group of heat-generating components 201 and heat-generating components 206
Are thermally connected to one heat sink 205 via different thermally conductive electrically insulating members 204. further,
In FIG. 1, not only the heat-generating component but also the non-heat-generating component 102 is mounted on the wiring board. However, only the heat-generating component 301 as shown in FIG. It may be configured to be thermally connected to the heat sink 304 via the member 303. A more preferable configuration is that the heat generating component 401 is mounted on one main surface of the wiring board 403 shown in FIG.
And the non-heat-generating component 402 is mounted only on the opposite surface. This is because even if the non-heat-generating component is extremely weak against heat, the function of the heat-generating component will not be impaired by the heat from the heat-generating component.

In the power module having such a structure, it is possible to mount the heat-generating components on the wiring board on which the fine wiring is formed with high density, and the heat generated from the heat-generating components is applied to the heat-generating components and the heat sink. Heat is instantly radiated from the heat sink via the heat conductive electrically insulating member that is bonded. Furthermore, the thermally conductive electrically insulating member is deformed in a complementary manner to absorb unevenness in height of the heat-generating components mounted on the wiring board, dimensional tolerances, and variations in mounting posture with respect to the wiring board. The heat generated from each heat generating component can be uniformly and efficiently dissipated without being affected by the variation of Further, since the heat conductive electrically insulating member is bonded to the heat generating component and the heat sink, the contact heat resistance is low and the heat radiation efficiency is high. Therefore, the power circuit unit including the heat-generating component and the control circuit unit including the non-heat-generating component can be integrated and mounted on the same wiring board with high density, and the power module can be further downsized. Further, since the heat conductive electrically insulating member is adhered by itself, no external force is required to bring it into close contact with the heat generating component, and there is no stress on the heat generating component. Therefore, the power module has higher reliability.

(Second Embodiment) FIG. 5 is a sectional view showing a structure of a power module according to a second embodiment of the present invention. In the second embodiment, another embodiment of the power module according to the present invention will be described. Unless otherwise specified, the materials used are those described in the first embodiment, and constituent members having the same names also have the same function.

FIGS. 5A-B show a preferred configuration example of the power module of the present invention when a semiconductor element is used as the heat generating component. The semiconductor element is not particularly limited, but for example, IGBT, MOS-FET, transistor, diode, IC (integrate circuit), LSI (la
rge scale integration) is used. A semiconductor chip (heat generating component) 501 in FIG. 5A is a bare chip, is mounted face down on a wiring board 503, and its back surface is bonded to the heat conductive electrically insulating member 504. As a result, since heat is radiated from the back surface of the semiconductor chip to the heat sink 505 while mounting is face down, high density mounting is possible, power loss is reduced and mounting heat is reduced as compared with mounting by wire bonding. You can also The face-down mounting method is not particularly limited, and various known methods can be used. For example,
A method of adhering the metal bumps 506 formed on the electrode surface of the semiconductor chip to the electrodes on the wiring board via solder or a conductive adhesive, or heating the semiconductor chip on which the metal bumps are formed face down. It is effective to apply pressure or ultrasonic waves to directly bond the metal bumps to the electrodes on the wiring board. At this time, it is preferable that the connecting portion between the semiconductor chip and the wiring pattern is sealed with resin 507. The sealing is not always necessary, but it serves to mechanically reinforce so as not to cause a failure of electrical connection during the subsequent steps, and therefore it is better in terms of workability.

The semiconductor chip (heat-generating component) 502 mounted face down in FIG. 5A is further electrically connected to the wiring board by connecting a metal conductor 508 to the back surface. Power semiconductors such as IGBTs and MOS-FETs that use silicon semiconductors or single crystal SiC semiconductors are
In general, there is a case where a current is made to flow in the thickness direction of the chip in order to cope with a large current, but the current from the back surface can be taken out through a metal conductor by the structure shown in the semiconductor chip 502 of FIG. 5A. Is preferred. The metal conductor is preferably at least one metal selected from copper, aluminum, nickel and iron. This is because the conductivity is high and the resistance loss is small even when a large current is applied.
In particular, copper is not only excellent in conductivity, but also has good thermal conductivity, and is therefore advantageous in improving heat dissipation.

The semiconductor element (heating component) 509 shown in FIG. 5B is provided with a heat spreader 512 on the backside in a resin-sealed state so as to expose at least a part thereof, and at least the exposed surface of the heat spreader is thermally conductive. Adhesive electrical insulating member 504. With this, the heat generated by the semiconductor element is instantaneously transmitted to the heat spreader, and the heat can be efficiently radiated toward the heat conductive electrically insulating member, which is a preferable configuration. Similarly, the semiconductor element (heat-generating component) 510 is also provided with a heat spreader 512 on the back surface, but a semiconductor chip having a structure in which an electric current is passed in the thickness direction is used, and an extraction electrode 513 is formed on the wiring board side of the heat spreader. It can also be used as a conductor for extracting a current from the back surface of the semiconductor chip. The semiconductor elements 509 and 510 are packaged as surface mount components, and take-out electrodes are provided from the electrode formation surface of the built-in semiconductor chip to the outside of the package. The extraction electrode is not particularly limited, but for example, a metal bump such as a lead frame 514 or a metal ball 515 made of at least one metal selected from copper, aluminum, nickel, iron and gold is preferable. The extraction electrode 513 from the back surface of the semiconductor chip formed on the heat spreader may be made of the same material as the extraction electrode from the electrode formation surface, or a protrusion may be formed on the wiring board side by subjecting the heat spreader to drawing. It is also possible to do so.

On the other hand, the semiconductor elements 509 and 510 are packaged and mounted as surface mount components.
After mounting the semiconductor chip (heating component) 511 having the heat spreader 512 on the back surface on the wiring board, the resin 516 including the semiconductor chip is provided between the heat spreader 512 and the wiring board 503 so that the heat spreader 512 exposes at least a part thereof. A sealed structure is also preferable. Since the connecting portion between the semiconductor chip and the wiring pattern and the semiconductor chip itself are also sealed, the structure has high reliability.

The heat spreader is preferably at least one metal selected from copper, aluminum, nickel and iron, but is preferably copper which is excellent in electrical conductivity and thermal conductivity. It is preferable that the surface of the heat spreader to be bonded to the thermally conductive and electrically insulating member be roughened in advance. This is because the adhesion becomes stronger. As the roughening treatment method, both a chemical treatment method and a physical treatment method can be adopted. Examples of the chemical treatment method include a method in which a heat spreader is immersed in an aqueous solution of iron chloride, copper chloride or the like and etching is performed.
In addition, as a physical treatment method, for example, a method of spraying powder of aluminum oxide or the like on the surface with compressed air can be mentioned.

(Embodiment 3) FIGS. 6A to 6D are cross-sectional views by step showing a method of manufacturing a power module according to Embodiment 3 of the present invention. In the third embodiment, an embodiment of a method of manufacturing the semiconductor device shown in FIG. 4 will be described.
Unless otherwise specified, the materials used are those described in each of the above-mentioned embodiments, and constituent members having the same names and manufacturing methods have the same function.

In FIG. 6A, the heat generating component 601 is mounted on the wiring board 603. The mounting method is not particularly limited,
Various known methods can be used. For example, a method using solder or a conductive adhesive is used for surface-mounted components, and a face-down mounting method as described in Embodiment 2 for semiconductor chips. 6A-
In D, the sealing resin in the connection portion between the semiconductor chip and the wiring pattern is omitted, but it is more preferably sealed. In this case, after mounting the semiconductor chip face down, a resin is injected into a desired portion and cured.

The wiring board is not limited to the double-sided wiring board as shown in FIG. 6A, and may be a multilayer wiring board. In the figure, the wiring pattern formed on the surface of the wiring board is omitted. Next, the uncured thermally conductive electrically insulating member 604 is disposed on one main surface of the heat sink 605. The heat conductive electrically insulating member is a heat conductive resin composition containing at least an inorganic filler and an insulating resin.

In FIG. 6B, the heat conductive resin composition obtained by kneading the above-mentioned inorganic filler and insulating resin is used as the uncured heat conductive electrically insulating member 604, and the heat sink 6 is used.
It is placed on one major surface of 05. As a placement method, application of a paste of the heat conductive resin composition having an appropriate viscosity is simple and preferable. As a coating method, for example, a metal mask printing method or the like can be adopted. In addition, a method of placing a heat conductive resin composition on a release film in a sheet state and laminating the sheet on a heat sink is excellent in handleability and is preferable. An extrusion molding method can also be used as a method of forming a sheet.

As the heat sink 605, it is preferable to use an aluminum plate or a copper plate having excellent heat conductivity, and it is more preferable to use one having a heat radiation fin. In particular, since aluminum is excellent in workability, it is possible to form the heat sink in a complicated shape to increase the surface area and to obtain good heat dissipation. In addition, on the surface of the heat sink, similar to the roughening treatment of the heat spreader surface described in the second embodiment,
It is preferable to perform roughening treatment in advance from the viewpoint of adhesiveness to the heat conductive electrically insulating member.

Next, in FIG. 6C, the uncured thermal conductivity disposed on the heat sink 605 is provided on the surface of the heat-generating component 601 mounted on the wiring board 603 opposite to the surface electrically connected to the wiring board. Press the electrical insulation member 604,
The heat-conducting electrically insulating member is complementarily deformed and brought into close contact with the irregular shape and height of the heat-generating component. To ensure that the heat-conducting electrically insulating member adheres to the heat-generating component or heat sink, 0.1 MPa or more and 20 MPa or more.
It is preferable to perform the treatment under the following pressure.

Then, the formed product is heat-treated in the above-mentioned preferable temperature range of 70 to 110 ° C. to absorb the liquid component contained in the insulating resin into the thermoplastic resin powder and swell the thermoplastic resin powder to obtain the uncured thermal conductivity. The viscosity of the electric insulating member is increased to irreversibly solidify, and the heat sink is fixed to the heat generating component. Since the heat conductive electrical insulation member is solidified but uncured, at this stage, the adhesion between the heat conductive electrical insulation member and the heat generating component or the heat sink is inspected. It is also possible to simply remove the thermally conductive electrically insulating member. As a result, the power module of the present invention can be manufactured with high yield.

Further, this is heated to cure the heat conductive electrically insulating member. The heating temperature may be equal to or higher than the curing temperature of the thermosetting resin contained in the heat conductive electrical insulating member, and is usually 130 ° C to 260 ° C, preferably 170 ° C to 230 ° C.
Is. In addition, this heating is also 0.1MPa or more and 20MP.
It is preferable to carry out under a pressure of a or less. This is because it is possible to reduce the voids in the heat conductive electrical insulating member that cause a decrease in the withstand voltage. In order to reduce the voids, the formation is subjected to a reduced pressure during the step of disposing and curing the heat conductive electrical insulating member or immediately after the heat generating component and the heat conductive electrical insulating member are brought into close contact with each other. Exposing is also effective.

In the present embodiment, the uncured thermally conductive electrically insulating member is solidified by the heat treatment to absorb the liquid component into the thermoplastic resin powder and swell the liquid component. This is a preferred embodiment that enables the repair process of the heat conductive electrically insulating member. However, a similar formed product can be obtained by heating and curing the uncured heat conductive electrical insulating member in close contact with the heat generating component and the heat sink. In this case, the insulating resin constituting the heat conductive resin composition may not contain the thermoplastic resin powder, and a composition containing at least a liquid thermosetting resin and a latent curing agent at room temperature is used. You can also

As described above, in FIG. 6C, the heat conductive electrical insulating member is cured and adhered to the heat generating component and the heat sink, and the power module having only the heat generating component shown in FIG. 3 described in the first embodiment is completed.

Next, in FIG. 6D, the non-heating component 602 is mounted on the surface of the wiring board 603 opposite to the mounting surface of the heating component by various known methods. As a result, the power module shown in FIG. 4 described in the first embodiment can be manufactured. If the mounting area of the non-heat generating component is not limited to the surface of the wiring board opposite to the mounting surface of the heat generating component, the first embodiment
The power module shown in FIG. 1 and described above can be manufactured. It should be noted that, in the above embodiment, a similar power module can be manufactured even if each step is carried out by using the wiring board in which the non-heat generating component is mounted together with the heat generating component in advance.

(Fourth Embodiment) FIGS. 7A and 7B are sectional views showing the structure of a power module according to a fourth embodiment of the present invention. In the fourth embodiment, another embodiment of the power module according to the present invention will be described. Unless otherwise specified, the materials used are those described in each of the above-described embodiments, and constituent members having the same names and manufacturing methods have the same function.

FIGS. 7A and 7B are examples of preferable configurations of the heat sink in the power module of the present invention. FIG. 7A has a configuration similar to that of FIG. Wiring board 7
A heat-generating component 701 and a non-heat-generating component 702 are mounted on 03, and the heat-generating component 701 is thermally connected to a heat sink 705 via a heat conductive electrically insulating member 704. However, the heat sink has a concave portion, and the heat generating component is housed in the concave portion via the heat conductive electrically insulating member. With this configuration, the arrangement of the uncured thermally conductive electrically insulating member is limited to the concave portion of the heat sink, so that excessive resin flow can be prevented and sufficient pressure at the time of adhesion can be obtained.
The power module of the present invention can be easily manufactured. In addition,
Non-heat generating components may be housed in the recess of the heat sink. Further, in FIG. 7A, the heat sink 705 and the wiring board 703 are in contact with each other, but the present invention is not limited to this, and another configuration is conceivable. For example, it does not have to be in contact with each other, and a region in which the heat sink and the wiring board are in contact with each other may be fixed using a fixing tool such as a screw.

As shown in FIG. 7B, the heat-conducting electrically insulating member 704 is used to generate the heat-generating component 701 and the non-heat-generating component 70.
2 may be sealed.

(Embodiment 5) FIGS. 8A to 8D are cross-sectional views by process showing a method of manufacturing a power module according to Embodiment 5 of the present invention. In the fifth embodiment, an embodiment of the power module and the manufacturing method thereof according to the present invention will be described. Unless otherwise specified, the materials used are those described in each of the above-mentioned embodiments, and constituent members having the same names and manufacturing methods have the same function.

In FIG. 8A, the heat generating component 801 is mounted on the wiring board 803.

Next, referring to FIG. 8B, the heat sink 80
The heat conductive electrically insulating member 80 in an uncured state on one main surface of No. 5
Place 4 The heat conductive and electrically insulating member is the third embodiment.
The heat conductive resin composition has the same structure as described in 1. and contains at least an inorganic filler and an insulating resin. The insulating resin that constitutes the heat-conductive resin composition contains a thermosetting resin that is liquid at room temperature as a main component, contains at least a thermoplastic resin and a latent curing agent, and in the uncured state, the thermoplastic resin is The composition is a plastic resin powder.

Further, in the present embodiment, at this stage, 7
The thermally conductive electrically insulating member is heat-treated in a preferable temperature range of 0 to 110 ° C., and the thermoplastic resin powder absorbs the liquid component contained in the electrically insulating resin so as to swell, so that the uncured thermally conductive electrically insulating member is obtained. Visibly increases the viscosity of and irreversibly solidifies.

Next, in FIG. 8C, the heat-generating component 801 mounted on the wiring board 803 is placed on the heat sink 805 on the opposite side of the surface electrically connected to the wiring board, but is in an uncured state but solid. Thermal conductive electrically insulating member 8
04 is pressed, and the heat conductive electrical insulating member is complementarily deformed and closely adhered to the uneven shape and height of the heat generating component. To ensure that the heat-conducting electrically insulating member adheres to the heat-generating component or heat sink, 0.1MP
It is preferable that the pressure is a or more and 20 MPa or less. In the present embodiment, the pressurization necessary for this close contact is carried out by fixing the heat sink to the wiring board with the fixture 806. The fixture is not particularly limited and, for example, a screw or the like can be used. By this fixing, necessary pressure can be obtained, and at the same time, the heat sink can be surely arranged with respect to the heat generating component, and the reinforcement is performed so as not to cause a deviation in the subsequent work, and the manufacturing can be more easily performed. The thermally conductive electrically insulating member, whose viscosity is increased and solidified by the swelling of the thermoplastic resin powder, is in an uncured state, and has flexibility to the extent that it is deformed with respect to the heat-generating component pressed. Even if the fluidity is high, it is possible to prevent an excessive excessive resin flow in the contacting process by heat-treating the heat conductive electrical insulation member before it is adhered to the heat generating component to solidify it. It is possible to obtain sufficient pressurization. Further, since the heat conductive electrical insulating member is solidified but is uncured, at this stage, the adhesion between the heat conductive electrical insulating member and the heat generating component or the heat sink is inspected, and a poor adhesion is temporarily generated. In some cases, the heat conductive electrically insulating member can be easily removed.
As a result, the power module of the present invention can be manufactured with high yield.

Next, this is heated to cure the heat conductive electrically insulating member. Further, in FIG. 8D, the non-heat generating component 802 is mounted.

As described above, the heat conductive electrically insulating member is cured and adhered to the heat generating component and the heat sink, and the power module in which the heat sink is fixed to the wiring board by the fixture is completed. The fixing of the heat sink to the wiring board may be performed after the heat conductive electrically insulating member is cured. Even in this case, the heat sink bonded to at least the heat-generating component by the heat-conductive electrically insulating member is more firmly fixed than the fixture, and has a structure excellent in impact resistance.

(Sixth Embodiment) FIGS. 9A to 9D are cross-sectional views for each process showing a method of manufacturing a power module according to a sixth embodiment of the present invention. In the sixth embodiment, an embodiment of the power module and the manufacturing method thereof according to the present invention will be described. Unless otherwise specified, the materials used are those described in each of the above-mentioned embodiments, and constituent members having the same names and manufacturing methods have the same function.

In FIG. 9A, the heat generating component 901 is mounted on the wiring board 903.

Next, referring to FIG. 9B, the uncured thermally conductive electrically insulating member 904 is placed on each heat generating component. The heat conductive electrically insulating member has the same structure as that described in the third embodiment and is a heat conductive resin composition containing at least an inorganic filler and an insulating resin. The insulating resin that constitutes the heat-conductive resin composition contains a thermosetting resin that is liquid at room temperature as a main component, contains at least a thermoplastic resin and a latent curing agent, and in the uncured state, the thermoplastic resin is The composition is a plastic resin powder.

Next, referring to FIG. 9C, the heat sink 90
5 is pressed against the uncured thermally conductive electrically insulating member 904 disposed on each heat generating component 901,
The heat-conducting electrically insulating member is complementarily deformed and brought into close contact with the irregular shape and height of the heat-generating component. To ensure that the heat-conducting electrically insulating member adheres to the heat-generating component or heat sink, 0.1 MPa or more and 20 MPa or more.
It is preferable to perform the treatment under the following pressure. Then, the formed product is heat-treated in a preferable temperature range of 70 to 110 ° C. to absorb the liquid component contained in the insulating resin into the thermoplastic resin powder so that the thermoplastic resin powder swells to obtain the viscosity of the uncured thermally conductive electrically insulating member. Is raised to irreversibly solidify and the heat sink is fixed to the heat-generating component. Since the heat conductive electrical insulation member is solidified but uncured, at this stage, the adhesion between the heat conductive electrical insulation member and the heat generating component or the heat sink is inspected. It is also possible to simply remove the thermally conductive electrically insulating member. As a result, the power module of the present invention can be manufactured with high yield.

Further, this is heated to cure the heat conductive electrically insulating member. In the present embodiment, the uncured thermally conductive electrically insulating member is solidified by heat-treating the thermoplastic resin powder to absorb the liquid component and swell, and thus the thermally conductive electrically conductive material described above is obtained. This is a desirable embodiment that enables the repair process of the insulating member.
However, a similar formed product can be obtained by heating and curing the uncured heat conductive electrical insulating member in close contact with the heat generating component and the heat sink. In this case, the insulating resin constituting the heat conductive resin composition may not contain the thermoplastic resin powder, and a composition containing at least a liquid thermosetting resin and a latent curing agent at room temperature is used. You can also

Next, referring to FIG. 9D, the non-heating component 902.
Implement.

As described above, the heat conductive electrically insulating member is adhered to each heat generating component to complete the power module having the structure thermally connected to one heat sink.

According to the structure and manufacturing method of the power module of the present embodiment, the required amount of the heat conductive and electrically insulating member is small, and the power module of the present invention can be manufactured at low cost.

The above embodiments do not limit the present invention, and other embodiments can be adopted based on the scope of the claims of the present patent.

[0102]

EXAMPLES The present invention will be described more specifically below with reference to examples.

Example 1 As a power module having a structure similar to that shown in FIG. 4, an inverter module having a drive circuit integrated therein was manufactured in the following manner. However, the electronic components to be mounted are not limited to those shown in FIG. 4, and are appropriately selected according to the circuit configuration. First, four layers of F with a wiring pattern formed
An R-5 type (manufactured by Matsushita Electronic Components Co., Ltd., a trade name, a wiring board obtained by impregnating a glass fiber woven fabric with an epoxy resin) was prepared. Next, electronic components including heat generating components were mounted on one surface of the wiring board to form a power circuit section. As an example of component mounting, for example, a semiconductor chip is mounted face down on a wiring pattern. As the semiconductor chip, an IGBT (made by Matsushita Electric Industrial Co., Ltd.) with a current of 50 A was used. The electrode of the semiconductor chip has a diameter of 100 μm and a height of 40
A μm bump was formed by a gold plating method, and eutectic solder was printed on the bump. The semiconductor chip was placed on the wiring pattern, and the eutectic solder was melted by the solder reflow device with the semiconductor chip fixed, and the electrodes of the semiconductor chip and the wiring pattern were electrically connected. Further, the space between the semiconductor chip and the wiring pattern was sealed with a liquid sealing resin.

Next, as a heat sink, a thickness of 2.0 mm
Was prepared, and one surface was roughened by sandblasting (polishing powder: Al ₂ O ₃ , Morundum A-40 (trade name), Showa Denko KK). A heat conductive resin composition was printed on the roughened surface to dispose a heat conductive electrically insulating member in an uncured state. As the heat conductive resin composition, a resin composition having the following composition is kneaded with a three-roll mill to obtain a viscosity of 30.
A viscous liquid (paste) of 0 Pa · s was used. (1) Inorganic filler: spherical Al ₂ O ₃ (“AS-40”,
Showa Denko KK, average particle diameter 12 μm) 88 parts by mass (2) Thermosetting resin: Bisphenol A type epoxy resin ("Epicoat 828", Yuka Shell Epoxy Co., Ltd.)
7.5 parts by mass (3) latent curing agent: tertiary amine salt-based latent curing agent ("
Amicure PN-23 ", manufactured by Ajinomoto Co., Ltd.) 1.0 part by mass (4) Thermoplastic resin powder: polymethylmethacrylate powder 3.0 parts by mass (5) Additive: carbon black (manufactured by Toyo Carbon Co., Ltd.)
0.3 parts by mass (6) Dispersant for inorganic filler ("Prysurf F-20
8F ", manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) 0.2 parts by mass The heat conductive resin composition is printed on a heat sink by setting the heat sink on a printing stage and opening a desired printed portion to form a stainless steel sheet having a thickness of 2.5 mm. The (SUS) metal mask was placed on the metal mask so as to come into contact with the heat sink, the heat conductive resin composition was dropped on the metal mask, and the stainless steel SUS plate squeegee was used to imprint the mask on the metal mask. After the removal, the exposed layer was exposed to a reduced pressure to remove the voids in the insulating layer.The rear surface of the group of heat-generating components mounted on the wiring board was placed on the arranged uncured thermally conductive electrically insulating member with a pressure of 0.5 MPa. Under the conditions described above, the heat conductive electrical insulating member was complementarily deformed and brought into close contact with the shape of the heat generating component and the height of the component were uneven. By holding and swelling the thermoplastic resin powder by absorbing the liquid component contained in the insulating resin, the uncured heat conductive electrical insulating member was solidified, and the heat sink was fixed to the heat generating component. In this state, visually inspected for the presence of defective adhesion between the heat conductive electrical insulation member and the heat-generating component or heat sink.If there is poor adhesion, remove the heat conductive electrical insulation member and remove it. It was re-produced by the same manufacturing method, and then this formed product was subjected to 6 ° C. at 175 ° C. without pressure.
It was heated for 0 minutes to cure the thermosetting resin in the heat conductive electrical insulating member and adhere it to the heat generating component and the heat sink. Finally, electronic components were mounted on the surface of the wiring board opposite to the surface on which the power circuit was formed to form a drive circuit.

The thickness of the heat conductive electrical insulating member of the obtained power module immediately below the heat generating component was 2 mm at maximum and 0.7 mm at minimum. From the observation with the ultrasonic flaw detector, it was confirmed that there was no void at the interface between the heat conductive electrical insulating member and the heat generating component or the heat sink.

When the withstand voltage of the heat conductive electrically insulating member was measured, a withstand voltage of 10 KV / mm or more was obtained. When the thermal conductivity of the power module was evaluated,
A thermal resistance value of 0.84 ° C / W was obtained. The thermal resistance value was calculated from the measured value by measuring the temperature of the back surface of the heat sink by supplying current to the semiconductor chip to generate heat.

As the reliability evaluation, the maximum temperature is 2
Reflow test for 10 seconds at 60 ° C. A reflow test was performed 10 times. At this time, the power module did not have cracks on its appearance, and no abnormalities such as peeling at the interface between the heat conductive electrical insulating member and the heat generating component or the heat sink were observed even when observed by an ultrasonic flaw detector.

Example 2 A power module having the same structure as that shown in FIG. 7 was produced in the following procedure. However, as a heat generating component of the mounted power circuit unit, a heat spreader (10 mm length × 10 mm width × 2 mm thickness) is attached to the semiconductor chip 511 configured to take out current from the back surface of FIG. 5B.
The semiconductor element provided with was selected. First, a heat spreader made of a copper plate was plated with nickel, and one surface of the heat spreader was bonded to the back surface of the semiconductor chip with solder. The semiconductor chip is an IGBT with a current of 50 A (made by Matsushita Electronics Industrial Co., Ltd.)
It was used. Further, a ball electrode made of ball-shaped copper having an average diameter of 2 mm and having a thickness of 1 μm was plated with gold was connected to the electrode of the semiconductor chip by an ultrasonic bonding device to form a metal bump. At the same time, a similar large ball electrode was ultrasonically connected and projected onto the heat spreader around the semiconductor chip to form a take-out electrode. Next, a four-layer FR-5 type glass epoxy wiring board on which a wiring pattern is formed is prepared, the semiconductor chip and the take-out electrode of the heat spreader are aligned on the wiring pattern, and they are bonded by an ultrasonic bonding device. did. Further, the space between the semiconductor chip and the wiring pattern was sealed with a liquid sealing resin. Then, the space between the heat spreader and the wiring board including the semiconductor chip was sealed with a liquid sealing resin so that only one surface of the heat spreader was exposed.

Next, as a heat sink, the thickness is 5.0 mm.
Depth of aluminum plate is 3.0mm, wall thickness is 2.0m
The thing which provided the recessed part of m was prepared, and the bottom face of the recessed part was roughened by sandblasting. A heat conductive resin composition was printed on the roughened surface to dispose a heat conductive electrically insulating member in an uncured state. As the heat conductive resin composition, a resin composition having the following composition was kneaded with a three-roll and used. (1) Inorganic filler: spherical Al ₂ O ₃ (“AS-40”,
Showa Denko KK, average particle diameter 12 μm) 85 parts by mass (2) Thermosetting resin: Bisphenol F type epoxy resin (“Epicoat 806”, Yuka Shell Epoxy Co., Ltd.)
8.5 parts by mass (3) latent curing agent: tertiary amine salt-based latent curing agent (“Amicure PN-23”, manufactured by Ajinomoto Co., Inc.) 1.5 parts by mass (4) thermoplastic resin powder: polyethylene powder 4 .5
Parts by mass (5) Additive: carbon black (manufactured by Toyo Carbon Co., Ltd.)
0.3 parts by mass (6) Dispersant for inorganic filler ("Prysurf F-20
8F "manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 0.2 parts by mass of the heat conductive resin composition was kneaded by an extrusion molding method.
A sheet having a thickness of 1.0 mm was formed on a release film of polyethylene terephthalate (PET) whose surface was subjected to a release treatment. This sheet material was cut into the opening shape of the recess of the heat sink, laminated so that the sheet surface was in contact with the recess of the heat sink, only the release film was peeled off, and the heat conductive resin composition was placed on the bottom surface of the recess of the heat sink. . This was held at 100 ° C. for 5 minutes to absorb the liquid component contained in the insulating resin into the thermoplastic resin powder and swell it to solidify the uncured thermally conductive electrically insulating member.
The rear surface of the group of heat-generating components mounted on the wiring board is pressed against the uncured but solidified thermally conductive electrical insulating member, and the concave portion of the heat sink is covered by the wiring substrate to make the heat-generating component The heat conductive electrically insulating member was complementarily deformed and adhered to the irregular shape and height of the parts. From the above, even if the fluidity of the heat conductive electrical insulating member is high, the heat conductive electrical insulating member is heat-treated to increase the viscosity by regulating the position in the concave portion of the heat sink and further heat-sealing the heat conductive electrical insulating member before closely contacting the heat generating component It was possible to prevent excessive resin flow in the step of closely contacting the heat-generating component, and to obtain sufficient pressure during contact. Next, this formed product was heated at 175 ° C. for 60 minutes without pressure to cure the thermosetting resin in the heat conductive electrical insulating member, and adhered to the heat generating component and the heat sink. Finally, electronic components were mounted on the surface of the wiring board opposite to the surface on which the power circuit was formed to form a drive circuit.

The obtained power module was confirmed by observation with an ultrasonic flaw detector to be free of voids at the interface between the heat conductive electrical insulating member and the heat generating component or heat sink.

When the withstand voltage of the heat conductive electrically insulating member was measured, a withstand voltage of 10 KV / mm or more was obtained. When the thermal conductivity of the power module was evaluated,
A thermal resistance value of 0.80 ° C./W was obtained.

As a reliability evaluation, after conducting a heat cycle test, the withstand voltage was measured.
A withstand voltage of mm or more was obtained, and there was no deterioration before and after the test. For the heat cycle test,
The operation of holding the material at a low temperature of 55 ° C. for 30 minutes and then at a high temperature of 125 ° C. for 30 minutes was repeated 1000 times.

The power module obtained in this embodiment is
On the back surface of the heat-generating component electrically connected to the wiring board, a thermally conductive electrically insulating member filled with a high concentration of inorganic filler,
Adhesion is uniform without being affected by variations in component height, and heat generated from heat-generating components can be efficiently transferred to the heat sink. Further, it becomes possible to mount the heat-generating components at a high density on the wiring board on which the fine wiring is formed, and the heat generated from the heat-generating components is transferred to the heat-generating components and the heat sink by the heat conductive electrically insulating member. Heat was radiated from the heat sink instantly through. Furthermore, the thermally conductive electrically insulating member is deformed in a complementary manner to absorb unevenness in height of the heat-generating components mounted on the wiring board, dimensional tolerances, and variations in mounting posture with respect to the wiring board. The heat generated from each heat generating component could be dissipated uniformly and efficiently without being affected by the variation of Moreover, since the heat conductive electrically insulating member is bonded to the heat generating component and the heat sink, the contact heat resistance is low and the heat dissipation efficiency is high. Therefore, the power circuit unit including the heat generating component and the control circuit unit including the non-heat generating component can be integrated and mounted on the same wiring board with high density, and the power module can be further downsized. Furthermore, since the heat conductive electrically insulating member is adhered by itself, no external force is required to bring it into close contact with the heat generating component, and there is no stress on the heat generating component. Therefore, the power module has higher reliability.

[0114]

As described above, according to the present invention, it is possible to achieve both fine wiring required for a heat-generating component having a large number of connection terminals and high heat dissipation, and a power module suitable for high-density miniaturization, and a manufacturing method thereof. Can be provided.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a power module according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a power module according to the first embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a power module according to the first embodiment of the present invention.

FIG. 4 is a sectional view showing a power module according to the first embodiment of the present invention.

FIG. 5B is a cross-sectional view showing a power module according to the second embodiment of the present invention.

6A to 6D are cross-sectional views for each process showing the method of manufacturing the power module according to the third embodiment of the present invention.

7A and 7B are cross-sectional views showing a power module according to a fourth embodiment of the present invention.

8A to 8D are cross-sectional views for each step showing the method of manufacturing the power module according to the fifth embodiment of the present invention.

9A to 9D are cross-sectional views for each process showing the method of manufacturing the power module according to the sixth embodiment of the present invention.

FIG. 10 is a graph showing a viscosity characteristic of a curable resin composition according to an example of the present invention.

[Explanation of symbols]

101,201,206,301,401,501,502,601,701,801,901 Heat-generating components 102,202,402,602,702,802,902 Non-heat-generating components 103,203,302,403,503,603,703,803,903 Wiring board 104,204,303,404,504,604,514,508,510,510,510,510 Heat-insulating components 105,205,304,405,505,505,505,505,505,505,505,505,505 Frame 515 metal ball 806 fixture

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Seiichi Nakatani             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F term (reference) 5F036 AA01 BA23 BB05 BB21 BB23                       BC03 BC22 BC33 BD01 BD03                       BD21 BE09

Claims (37)

[Claims] 1. A power module in which a heat generating component electrically connected to a wiring board and a heat sink are connected via a heat conductive electrical insulating member, wherein the heat conductive electrical insulating member is thermosetting. Resin (A),
A curing composition comprising a thermoplastic resin (B), a latent curing agent (C) and an inorganic filler (D), wherein the heat conductive electrically insulating member has uneven shapes and heights of the heat generating components. In contrast, the power module is adhered to the heat-generating component in a complementary state, and radiates heat generated from the heat-generating component by the heat sink. 2. A total amount of 100 parts by mass of the thermosetting resin (A) of 50 parts by mass or more and 95 parts by mass and the latent curing agent (C) of 5 parts by mass or more and 50 parts by mass or less. ,
The thermoplastic resin (B) is in the range of 10 parts by mass or more and 100 parts by mass or less, and the total amount of the thermosetting resin (A), the thermoplastic resin (B), and the latent curing agent (C) is 5 The amount of the inorganic filler (D) is 70 parts by mass or more and 95 parts by mass or more with respect to 30 parts by mass or more.
The power module according to claim 1, which is in a range of not more than mass parts. 3. The thermosetting resin is liquid at room temperature,
The power module according to claim 1, wherein the thermoplastic resin is powdery when the thermosetting resin is uncured. 4. The power module according to claim 3, wherein the thermosetting resin that is liquid at room temperature is a liquid epoxy resin. 5. A curable composition containing the thermosetting resin (A), a thermoplastic resin (B), a latent curing agent (C) and an inorganic filler (D) is 70 ° C. or higher and lower than 130 ° C. The power module according to claim 1, wherein the power module has the characteristics of a steep first-order viscosity increase curve at 10 ° C. and a steep second-order viscosity increase curve at 130 ° C. or higher. 6. The power module according to claim 1, wherein the heat conductive electrically insulating member is bonded to the plurality of heat generating components. 7. The power module according to claim 1, wherein a non-heat generating component is further mounted on the wiring board. 8. The power module according to claim 6, wherein the heat-generating component is mounted on one main surface of the wiring board, and the non-heat-generating component is mounted on the opposite surface. 9. The inorganic filler is Al ₂ O ₃ , Mg
The power module according to claim 1, which is at least one filler selected from O, BN, SiO ₂ , SiC, Si ₃ N _4, and AlN. 10. The power module according to claim 1, wherein the thermal conductivity of the thermally conductive electrically insulating member is in the range of 1 to 10 W / mK. 11. The power module according to claim 1, wherein the heat generating component is at least one semiconductor element. 12. At least one of the semiconductor elements comprises:
A heat spreader is provided on the surface opposite to the surface electrically connected to the wiring board, and the heat spreader is resin-sealed with at least a portion exposed, and at least the exposed surface of the heat spreader is the thermal conductive electricity. The power module according to claim 11, which is bonded to an insulating member. 13. The power according to claim 11, wherein the semiconductor element is a semiconductor chip, the semiconductor chip is mounted face down on the wiring board, and a back surface of the semiconductor chip is bonded to the thermally conductive and electrically insulating member. module. 14. The semiconductor element is a semiconductor chip, the semiconductor chip is mounted face down on the wiring board, and a back electrode of the semiconductor chip is electrically connected to the wiring board via a metal conductor. The power module according to claim 11, which is provided. 15. The power module according to claim 14, wherein a resin is sealed between the semiconductor chip mounted face down and the wiring board. 16. The power module according to claim 11, wherein the semiconductor chip is at least one semiconductor selected from a silicon semiconductor and a silicon carbide semiconductor having a structure in which a current flows in the thickness direction. 17. The power module according to claim 1, wherein the heat sink is aluminum or copper. 18. The power module according to claim 1, wherein the heat sink is fixed to the wiring board by a fixing tool. 19. The power module according to claim 1, wherein the heat sink has a concave portion, and at least the heat-generating component is housed in the concave portion via the thermally conductive electrically insulating member. 20. The power module according to claim 1, wherein the heat sink includes a radiation fin. 21. The power module according to claim 1, wherein the heat generating member is a plurality of heat generating components having different heights. 22. The power module according to claim 1, wherein a complementary state of the heat conductive electrically insulating member is molded by pressing. 23. A step of mounting an electronic component including at least a heat-generating component on a wiring board, a thermosetting resin (A), a thermoplastic resin (B), a latent curing agent (C) and an inorganic filler ( A curable composition layer containing D) is formed between the heat sink and the heat generating component side of the wiring board, and at least one selected from the heat sink and the wiring substrate is pressed against the other, and the shape and components of the heat generating component are formed. Complementary deformation and adhesion of the thermally conductive electrically insulating member to the uneven height, and heating to cure the curable composition layer to form the thermally conductive electrically insulating member. And a method for manufacturing a power module. 24. The total amount of 100 parts by mass of the thermosetting resin (A) is 50 parts by mass or more and 95 parts by mass or less and the latent curing agent (C) is 5 parts by mass or more and 50 parts by mass or less. The thermoplastic resin (B) is in the range of 10 parts by mass or more and 100 parts by mass or less, and the total amount of the thermosetting resin (A), the thermoplastic resin (B), and the latent curing agent (C). The inorganic filler (D) is 70 parts by mass or more and 95 parts by mass or more with respect to 5 parts by mass or more and 30 parts by mass or less.
The method for manufacturing a power module according to claim 23, wherein the content is within the range of parts by mass or less. 25. The method of manufacturing a power module according to claim 23, wherein the thermosetting resin is liquid at room temperature, and the thermoplastic resin is powdery when the thermosetting resin is uncured. 26. The method of manufacturing a power module according to claim 25, wherein the thermosetting resin that is liquid at room temperature is a liquid epoxy resin. 27. The curable composition containing the thermosetting resin (A), the thermoplastic resin (B), the latent curing agent (C) and the inorganic filler (D) is 70 ° C. or higher and lower than 130 ° C. 24. The method of manufacturing a power module according to claim 23, which has the characteristics of a steep first-order viscosity increase curve at 10 ° C. and a steep second-order viscosity increase curve at 130 ° C. or higher. 28. The method of manufacturing a power module according to claim 27, wherein the primary viscosity increase curve is a viscosity increase due to the thermoplastic resin powder absorbing and swelling the liquid component by heating. 29. The method of manufacturing a power module according to claim 23, wherein solidification is performed at a temperature of 70 ° C. or higher and lower than 130 ° C., and curing is performed at a temperature of 130 ° C. or higher and 260 ° C. or lower. 30. The step of mounting a heat-generating component on the wiring board, after mounting the semiconductor chip face down,
24. The method of manufacturing a power module according to claim 23, which is a step of injecting a sealing resin between the wiring pattern on the wiring board and the semiconductor chip and curing the resin. 31. The curable composition is at least one selected from a paste-like material and a sheet-like material.
A method for manufacturing the power module according to. 32. The method of manufacturing a power module according to claim 23, wherein a pressure for bringing the heat sink and the wiring board into close contact with each other is 0.1 MPa or more and 200 MPa or less. 33. The pressure for heat curing is 0.1M.
The method for manufacturing a power module according to claim 23, wherein the Pa is 200 MPa or more and 200 MPa or less. 34. The method of manufacturing a power module according to claim 23, wherein the heat sink and the wiring board are brought into close contact with each other and then placed in a reduced pressure atmosphere. 35. A surface of a semiconductor chip is provided with a metal ball, a wiring board is provided on the surface of the semiconductor chip, a heat spreader is closely provided on the entire back surface of the semiconductor chip, and heat is radiated from the heat spreader side, and the semiconductor chip has a thickness direction. Current is flowed to the heat spreader and the wiring board is electrically connected to the semiconductor chip between the wiring board and the heat spreader. Power module stopped. 36. A heat sink is further connected to the outside of the heat spreader via a heat conductive electrical insulating member, and the heat conductive electrical insulating member comprises a thermosetting resin (A),
The power module according to claim 35, which is a curing composition containing a thermoplastic resin (B), a latent curing agent (C) and an inorganic filler (D), and radiates heat generated from the semiconductor chip by the heat sink. . 37. A total amount of 100 parts by mass of the thermosetting resin (A) of 50 parts by mass or more and 95 parts by mass or less and the latent curing agent (C) of 5 parts by mass or more and 50 parts by mass or less. The thermoplastic resin (B) is in the range of 10 parts by mass or more and 100 parts by mass or less, and the total amount of the thermosetting resin (A), the thermoplastic resin (B), and the latent curing agent (C). The inorganic filler (D) is 70 parts by mass or more and 95 parts by mass or more with respect to 5 parts by mass or more and 30 parts by mass or less.
37. The power module according to claim 36, which is in a range of not more than mass parts.